statistic and Probability

5) A station is to be assigned a five-letter call sign. If the first letter must be an A or F, how many call signs are possible?(Letters may be repeated.) 6) A person needs a 4-letter code for a computer program. The letters A, F, and H cannot be used, and letters next to each other cannot be the same. How many passwords are possible if there is no difference between lowercase and uppercase? 7) A school social group has 30 seniors, 38 juniors, 24 sophomores, and 18 freshmen. They need to choose a president, an assistant, and an accountant. The president must be a senior and the assistant must not be a freshman. How many different ways can they pick the officers? 8) A person wants to make a five-letter word in a game. If the person has seven distinct letter tiles to choose from, how many words can the person make? (Assuming any combination of those five chosen letters can form a word) 9) Sharon is getting a license plate change and she must select seven characters. The first five must be letters, and the last two must be numbers. Repetition is allowed. If the letters R, G, Z, and the number 9, and 7 cannot be used, how many plates are possible? Page 2